1. Field of the Invention
The invention concerns an adjustment device for a vehicle seat having a back and a seat part formed by a seat substructure and a seat cushion with a side part and which is guided longitudinally by tracks, which can selectively regulate the seat part with respect to height, tilt or longitudinal distance wherein the adjustment device is formed of at least one planetary gear system which is positionally fixed, for example on the seat sub-assembly, on the side part or on the seat track, and is provided in a drive gear housing, which planetary gear system comprises at least one sun gear, at least on planet pinion as well as at least one ring gear, wherein the at least one sun gear in acted upon by rotation drive means for operation of the adjustment device.
2. Description of the Related Art
It is generally known that the seats in modern vehicles are adjustable with respect to multiple parameters to thereby provide an ergonomically comfortable seating position for the person seated thereupon. Therein it is of particular consequence to adjust, besides the adjustment position of the seat back, the adjustment of the seating surface, that is, the seat part with the seat cushion, in the length, height and tilt.
An adjustment device of the above described type is generally known from DE-OS 28 36 005, which shows the kinematics of the seat adjustment as well as the associated adjustment elements, which work in cooperation with the individual seat components. A seat substructure is connected to the vehicle chassis via front and rear pivotably coupled pivotable levers and is adjusted in height by appropriate tilting of these pivot levers. On this seat substructure a carrier part is provided, on which at the front at least one knuckle joint is coupled for tilt adjustment of the side part, of which the other end is connected with a seat part. The whole seat unit is guided on a track mounted on the vehicle floor and is longitudinally adjusted by means of a rack in engagement with an associated pinion or a spindle with a spindle nut.
In order to adjust the seat in height, torque is applied in the conventional manner to a linkage point of the 4-point-kinematic a torque is applied by means of a by a tooth segment of a pinion rotating about the linkage-rotating-point.
The same operating principle is employed by as rule for tilt adjustment, for this a further lever is employed at the front besides the 4-point-kinematic or by configuration of a 5-kinematic.
An adjustment device with the above described characteristics, that is, with adjustment means for adjusting the longitudinal, height and tile positions of a vehicle seat, is known from U.S. Pat. No. 4,765,582. Herein each adjustment means engages both sides of the vehicle seat and has either a lever mechanism for the manual operation or respectively one electrically operated adjustment means for each side and adjustment device.
The adjustment devices are respectively comprised of an intermediate or reduction gear and a planetary gear, each of which are provided with four planet pinions, which are secured to a planet pinion carrier and which are in engagement with an associated sun gear. The intermediate or reduction gears are respectively driven by flexible shafts from an assigned electro-motor provided below the corresponding seat, that is, the assigned drive motor acts upon two adjustment devices. This sets a minimal size for the motors. Further, a simple conversion from manual operation to motor operation is not possible, rather it requires a complete change-out of the adjustment devices. This is on the one hand expensive and on the other hand requires the stockpiling of extra spare parts.
Beginning with this state of the art it is the object of the present invention to provide an adjustment device for a vehicle seat of the above described type for the longitudinal-, height- and tilt adjustment thereof, which is simple to operate and which operates reliably both by means of manual operation as well also electro-motor and exhibits a high degree of self-retardation or self-locking during vehicle crash. In particular the device should be versatile in venues of employment.
In accordance therewith the adjustment device according to the invention is comprised of a planetary gear system which is positionally fixed, for example on the seat substructure, the side part or the seat track, and provided in a drive gear housing, and which includes at least one sun gear, at least one planet pinion as well as at least one ring gear, wherein the at least one sun gear is acted upon by a rotation driving device for operation of the adjustment device.
Preferably the planetary gear system includes two planet pinions with a first and with a second ring gear as well as with at least a common planet pinion, which is in engagement with a common sun gear.
Therein the first ring gear and the second ring gear advantageously exhibit respectively a gearing with differential modulus (m=t/.pi.), whereby a different rotation angle results upon operation of the common sun gear.
In a preferred embodiment of the invention it is envisioned that the first ring gear is provided at a fixed location and that the second ring gear rotates concentrically relative to the first ring gear and serves as adjustment element. Thereby, and on the basis that one of the two ring gears has a gear ring with a different modulus, it is achieved that upon rotation of the common sun gear the rotationally moveable ring gear rotates with respect to the fixed ring gear.
According to a preferred further embodiment of the invention, the rotation driving device is formed as an electro-motor, which via an attached gear acts upon the common sun gear. Thereby it is advantageous when the motor is connected to the gear housing and together therewith forms a single construction component.
According to an alternative embodiment a manual gear can be provided as rotation drive means, which acts upon the common sun gear. A supplemental gear is not necessary in this case and can be dispensed with, since the size of the hand wheel on the one hand and the magnitude of the torque to be applied on the other hand provide for a problem free operation by hand.
According to a further embodiment of the invention a spring element is provided for taking up of slack between the drive gear housing and the ring gear, which tensions the ring gear against the drive gear housing. Therein the torque of the engagement between the first and the second ring gear as well as the common sun gear and the at least one planet pinion results in a capturing or trapping of the tooth flank due to the spring force of the spring element, whereby both friction as well as noise generation are reduced.
In a further advantageous embodiment of the invention, selectively the first or second ring gear are provided fixed against rotation on the seat substructure, on the side part or on a seat track guided on a lower track, while the other respectively rotationally moveable ring gear operates or actuates the seat part for height, tilt or distance adjustment of the vehicle seat. It is advantageous when herein the respective rotationally moveable ring gear is provided with a lever, which lever acts upon the seat part.
According to a further preferred embodiment of the invention the first ring gear is provided fixed against rotation and serves as drive gear housing while the rotationally moveable second ring gear works in cooperation with the seat part as adjustment element.
According to a working embodiment of the inventive adjustment device for longitudinal adjustment of the vehicle seat the gear housing is provided on the seat part, preferably on a guide track associated with the seat part, and the rotationally moveable ring gear is connected to a pinion fixedly against rotation, which is in engagement with a positionally fixed rack associated with the lower track and therewith makes possible the longitudinal adjustment of the vehicle seat.
For the height adjustment of the vehicle seat according to another embodiment of the inventive adjustment device, the respective rotational ring gear is connected with a pivot lever of a first pivot lever pair and acts upon this, wherein the pivot lever is respectively pivotably connected to appropriate mounting points on the seat subassembly and on the upper track and connects these with each other.
In a third embodiment of the inventive adjustment device the respective rotationally moveable ring gear is connected with a pivot lever of a second pivot lever pair and acts upon this, wherein also here the pivot levers are respectively pivotably connected in appropriate mounting points on the side part and on the seat cushion and thereby connects these with each other. In this third adjustment device the ring gear connected with the second pivot lever adjusts the tilt of the seat part.
Advantageously in further embodiment of the invention the respective rotational moveable ring gear with the pivotable first or second pivot lever can form a single construction component, that is, in place of a, for example, rod shaped lever the rotationally moveable ring gear is connected at two points respectively with the seat components which are moveable relatively to each other, for example, connecting the side part and the seat cushion for the tilt adjustment, or connecting the side part or the seat subassembly with the upper track for the height adjustment.
Advantageously the force transmitting elements of the adjustment device are self-retardingly engaged with each other. Thereby it is achieved, that a completed seat adjustment does not change by itself and thus a supplemental locking mechanism or adjustment fixing mechanism can be dispensable with.
A further preferred embodiment of the invention envisions on each vehicle seat three positionally fixed adjustment devices, wherein of these respectively one serves as adjustment device for adjustment of the height of the seat part, one serves for adjustment of the tilting of the seat cushion and one serves for longitudinal adjustment of the vehicle seat, and wherein each adjustment device is controllable independently of each other.
Therewith it is ensured that each occupant can adjust the respective seat to the best position.
In view of the space limitations which among other things are important considerations in a vehicle, it can be of advantage when the drive unit, for example only the motor alone or the electro-motor with the associated gear which acts upon the common sun gear of the planetary gear system, is provided in a different place spatially separated from the location of the ring gear in the area of the vehicle seat. By this variation of the invention the planetary gear system drive units and the rotation driving device with associated gear are connected with each other selectively by a rigid or a flexible drive element. With this unique feature of the inventive adjustment device it becomes possible to optimize the design of the vehicle seat, without being hindered by the space requirement of the necessary drive units.
Particularly considering the simplification of the process of the assembly of the preferably three common planet pinions of the inventive adjustment device, according to a further advantageous embodiment of the invention a free stem disk is provided concentrically to the common sun gear, which is provided with a number of stems or arms corresponding to the number of planet pinions to be guided, which rotationally receives the planet pinions, and by means of which these are held both radially to the sun gear and to the ring gear in the correct separation.
These and further advantageous embodiments and improvements of the invention are characteristics of the dependent claims.